Yarn having variable shrinkage zones

ABSTRACT

A multi-filament yarn including interlace nodes disposed along the length of the yarn. The yarn has variable retained heat shrinkage potential at segments along its length such that segments of said yarn containing the interlace nodes have a retained heat shinkage potential in excess of segments of said yarn between the interlace nodes. Upon application of uniform heat to the yarn, the segments containing the interlace nodes exhibit enhanced shrinkage and self texturing relative to the segments between the interlace nodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior copending U.S.application Ser. No. 10/613,240, filed Jul. 3, 2003 entitled Pile Fabricand Heat Modified Fiber and Related Manufacturing Process and acontinuation-in-part of prior copending U.S. application Ser. No.10/613,241 filed Jul. 3, 2003 entitled Method of Making Pile Fabric thecontents of all of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present invention relates generally to fabric formation yarns andmore particularly to multifilament yarns in which discrete segmentsalong the length undergo enhanced selective shrinkage resulting in selftexturing and reduced crystalline orientation relative to other portionsof the same yarn. A method of imparting the variable performancecharacteristics to the yarns is also provided.

BACKGROUND OF THE INVENTION

In the past, partially oriented yarns (POY) of multi-filamentconstruction have typically been drawn and heatset under tension so asto extend and orient the individual filaments. In such a process each offilaments in the yarn is subjected to a substantially uniform heatingand extension treatment such that the yarn will thereafter act in auniform manner upon post fabric formation treatments such as heatsetting, dyeing and the like. That is, since the yarn has been uniformlytreated it does not exhibit variable response characteristics in afabric when subjected to heating or other treatment conditions.

It is also known to under draw yarns under uniform heat treatment toless than full orientation for subsequent formation into a fabric. Sucha process is illustrated and described in U.S. Pat. No. 5,983,470 toGoineau the contents of which are incorporated herein by reference intheir entirety. The resultant fabric has a generally striated appearanceupon dyeing.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides advantages andalternatives over the known art by providing a fabric formation yarnhaving variable shrink characteristics at different segments (alsoreferred to as zones) along its length such that when such yarn issubsequently subjected to heat such as in fabric finishing treatments,discrete portions of the yarn undergo selective shrinkage and selftexturing. The shrinking of segments along the yarn yields unshrunkenyarn segments of substantially parallel, oriented fibers in combinationwith shrunken yarn segments of self textured filaments with reducedcrystalline orientation in the same yarn.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only, withreference to the accompanying drawings which constitute a portion of thespecification herein and wherein:

FIG. 1 illustrates schematically a practice for hot drawing amulti-filament yarn to impart variable shrink characteristics at zonesalong the length of such yarn;

FIG. 2 is a block diagram setting forth steps for forming a variablesurface texture fabric;

FIG. 3 illustrates a partially oriented non-textured multi-filament yarnprior to hot drawing;

FIG. 4 is a graphical representation illustrating the cross-sectionalprofile of yarn filaments at different zones along the length of theyarn of FIG. 3 during hot drawing;

FIG. 5 is a photomicrograph of a circular knit sock illustratingvariable shrinkage segments of a fabric formation yarn;

FIGS. 6A and 6B are x-ray diffraction patterns for high shrink and lowshrink portions of a formation yarn respectively;

FIGS. 7A and 7B are angular distribution plots of select diffractionpeaks for high shrink and low shrink portions of a formation yarnrespectively;

FIG. 8 illustrates a tricot knit fabric incorporating a fabric formationyarn with variable shrinkage segments following hot drawing and postformation heat treatment wherein zones of the fabric formation yarn haveundergone selective shrinkage and self texturing;

FIG. 9 is a photomicrograph of fiber cross-sections in low shrinkportions of a formation yarn according to the present invention; and

FIG. 9A is a photomicrograph of fiber cross-sections in high shrinkportions of a formation yarn according to the present invention at thesame magnification as FIG. 9.

While the present invention has been generally described above and willhereinafter be described in greater detail in relation to certainillustrated and potentially preferred embodiments, procedures andpractices it is to be understood that in no event is the invention to belimited to such illustrated and described embodiments, procedures andpractices. Rather, it is intended that the invention shall extend to allembodiments, practices and procedures as may be embodied within thebroad principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, according to a potentially preferred practice ofthe present invention a yarn sheet 130 formed from a plurality of yarns122 is passed from a creel 131 through a drawing apparatus 132 to atake-up 133. The yarns 122 are so called “partially oriented yarns” ofmulti-filament construction wherein the filaments 126 (FIG. 3) have beeninterlaced at discrete zones along the length of the yarn. In practiceit is contemplated that the yarns are formed from a heat shrinkablematerial, such as a thermoplastic. By way of example only and notlimitation, exemplary fiber materials may include polyester,polypropylene, nylon and combinations thereof. As will be appreciated,when such materials are extruded from a melt solution into drawnfilaments, those filaments have an intrinsic finite shinkage potentialwhich is activated upon subsequent heat exposure. During heat exposureshinkage will proceed until the shinkage potential is exhausted or theheating is terminated.

As shown, the drawing apparatus 132 has a first draw zone 136 locatedbetween tensioning rolls 138, 140 and a second draw zone 142 locatedbetween tensioning rolls 140 and 146. A contact heating plate 150 aswill be well known to those of skill in the art engages the yarns 122within the second draw zone 142. According to the potentially preferredpractice, the partially oriented yarns 122 are passed through the firstdraw zone 136 with substantially no heating or drawing treatment. Thus,the yarns 122 are substantially unaltered upon entering the second drawzone 142. At the second draw zone the yarns 122 preferably undergo arelatively slight drawing elongation while simultaneously beingsubjected to a relatively low temperature heating procedure from thecontact heater 150. Since the resultant yarn 122′ is not drawn to acondition of full orientation it is referred to as “underdrawn” yarn.

According to the potentially preferred practice the yarn is conveyedacross the contact heater 150 at a high rate of speed such that the yarndoes not reach a state of temperature equilibrium within thecross-section of the yarn at all segments along its length. By way ofexample only, and not limitation, for a 115 denier polyester yarn it hasbeen found that subjecting such yarn to a draw ratio of about 1.15 (i.e.15% elongation) with a contact heater temperature of about 170 C. toabout 200 C. with a take up speed of about 500-600 yards per minuteprovides the desired non-uniform cross-sectional heat treatment at somesegments of the yarn while yielding a uniform cross-sectional heattreatment at other segments. Of course, the level of drawing,temperature and speed may be adjusted for different yarns.

The resultant yarn 122′ may then be formed into a fabric and heattreated to provide desired surface characteristics in the manner as willbe described further hereinafter. Of course, it is also contemplatedthat the yarn 122′ may be subjected to heat treatment prior tointroduction into a fabric if desired. In either case, discrete segmentsof the yarn 122′ undergo shrinkage and self-texturing while othersegments along the same yarn experience little if any change.

The mechanism believed to be responsible for the non-uniform characterof the yarns is believed to relate to the nature of the partiallyoriented yarn 122 being processed as well as the process conditions.Referring to FIG. 3, a representative illustration is provided of apartially oriented yarn (POY) 122 such as may be treated according tothe practice described above. As illustrated, the yarn 122 of partiallyoriented construction is characterized by loose segments 151 in whichthe individual filaments 126 are disposed in generally parallel alignedloose orientation relative to one another. These loose segments 151 areinterspersed by discrete interlace nodes 152 in which the filaments areinterlaced in a more compacted relation so as to hold the overall yarn122 together. The cross-sectional heat transfer characteristics of theloose segments 151 are believed to be substantially different from thatof the interlace nodes 152 and the yarn portions immediately adjacentsuch nodes.

In FIG. 4 a graphical illustration of the fiber cross-section isprovided showing the relative response of the filaments 126 in the loosesegments 151 and interlace nodes 152 of the yarn during heating underslight draw conditions as described above. In particular, what is seenis that the filaments within the loose segments 151 are pulled towardsthe heater by a combination of tensioning and heat shrinkage so as toassume a relatively low cross-sectional profile orientation across thecontact heater 150. This low cross-sectional profile allows those zonesto receive a substantially uniform and complete heat treatment despitethe high speed of travel across the heater. Conversely, the relativelyslight degree of draw applied is inadequate to pull out the interlacenodes 152. Thus, flattening and spreading of the filaments at theinterlace nodes is avoided. Thus, upon high speed underdrawingconditions the yarn portions around the interlace nodes 152 retain ahigher more concentrated profile across the heater 150 rather thanflattening out like the loose segments 151.

It is surmised that due to the lack of flattening and the high rate oftravel across the heater, heat treatment is not uniform within theinterlace nodes and adjacent portions. Thus, a significant number of thefilaments at those areas retain a relatively high level of shrinkagepotential since a steady state temperature is not reached. The retentionof such shinkage potential leaves such segments susceptible tosubsequent enhanced heat shrinkage relative to the remaining portions ofthe yarn (which have been subjected to uniform temperature treatment)upon subsequent heat application.

Variable Shrinkage and Bulking Evaluation

The enhanced retained shrinkage potential of the yarn at the interlacenodes relative to the intermediate loose zones following the treatmentprocess as outlined above has been confirmed by cutting out segments ofan exemplary 260 denier polyester yarn treated according to theprocedure outlined above and thereafter subjecting those cut outsegments to a uniform heat treatment and then measuring the level ofshrinkage caused by the heat treatment. In particular, a first group oftwo yarn segments was cut out from sections between interlace nodes suchthat each of the two cut out yarn segments in this first group wassubstantially devoid of any interlace node. A second group of three yarnsegments was cut out from the yarn such that each of the three cut outyarn segments in this second group was formed substantially of a singleinterlace node. Both the first group and the second group of yarnsegments were then subjected to a high temperature superheated steamtreatment to observe shrinkage. The results are set forth in Table Ibelow showing that the second group of yarn segments formed from theinterlace nodes exhibited substantially increased shrinkage on apercentage basis relative to the yarn segments in the first group devoidof interlace nodes. TABLE I Percent Shrinkage Sample Segment After HeatTreating Sample 1 - Interlace Node Segment 43% Sample 2 - Interlace NodeSegment 40% Sample 3 - Interlace Node Segment 33% Sample 4 - NoInterlace Nodes 10% Sample 5 - No Interlace Nodes  0%

In addition to shrinkage, it was also observed that the yarn segmentsformed from the interlace nodes underwent an enhanced degree of bulkingand self texturing resulting in substantial filament thickening in asignificant portion of the filaments.

Crystalline Orientation Evaluation:

It has also been found that after heat treatment (such as occurs infabric finishing) segments of the same yarn treated according to theprocedures as previously described are characterized by substantiallydifferent levels of crystalline orientation as measured by wide anglex-ray diffraction. In order to characterize the molecular structure ofthe two different types of domains in a finished construction, apolyester yarn treated according to the process as illustrated anddescribed in relation to FIG. 1 was circularly knitted into a sock (i.e.a tube), dyed, and finished. The finished sock exhibited two distincttypes of courses: open courses consisting of yarn that had low shrinkageduring finishing, and tight courses consisting of yarn that had highshrinkage during finishing. FIG. 5 illustrates a zone in the sockcontaining these two regions. Importantly, it is to be understood thatthe same yarn is used throughout the sock and that the different zonesemerged only after subsequent heat treatment.

To understand the differences in the zones of the sock individualcourses of each type of region were removed from the construction forx-ray measurement. Courses were ‘double-folded’ to form a 4-ply yarn soas to increase the scattering signal rate and reduce the necessaryexposure time. Samples were mounted onto standard x-ray sample mounts.

Wide-angle diffraction patterns were generated via exposure to x-raysgenerated with a rotating copper anode source having a primarywavelength of 1.5418 Å. Patterns were recorded using a general areadetector system offset to an angle of 2θ=16.5° and set 15 cm from thesample position. Samples were oriented in the beam such that the fiberaxis was vertical. Exposures of 15 minutes were used to generatepatterns, and a background pattern acquired over an empty position onthe sample holder was subtracted from the resulting data.

The diffraction pattern for the high-shrink yarn sample is shown in FIG.6A and that for the low-shrink yarn is shown in FIG. 6B wherein thelighter zones identify higher reflection intensity levels.Qualitatively, it was observed that in the two patterns the crystalplane reflections (the broad intensity peaks) in the high-shrink samplehave a greater azimuthal spread than those in the low-shrink sample. Itis known that the two primary causes of azimuthal spreading inmultifilament fiber samples are misalignment of individual filaments anddifferences in the angular distribution of crystallites between thesamples. Great care was taken during sample preparation to properlyparallelize the filaments, and a slight tension was applied to maintaingood orientation during handling and measurement. Thus, it is veryunlikely that filament disorientation alone can account for thedifferences in angular peak distribution observed in the patterns.Therefore, it was determined that the azimuthal spread reflects a realdifference in the angular distribution of crystallites between the twosamples.

It is known that the difference in the angular distribution ofcrystallites between the two samples can be quantified in terms of theHerman orientation function:$f_{c} = \frac{{3\left\langle {\cos^{2}\sigma} \right\rangle} - 1}{2}$where σ is the relative angle of the PET chain axis. As will beappreciated, the Herman orientation function is a measure of theorientation of PET chains within fiber crystallites with respect to thefiber axis direction. It assumes values ranging from +1 (perfectlyoriented parallel to the axis) to 0 (perfectly random) to −½ (perfectlyoriented perpendicularly). For cylindrically symmetric (on average)fibers, the distributional average of the square cosine term is givenby:$\left\langle {\cos^{2}\chi} \right\rangle = {\frac{\int_{0}^{\pi}{\cos^{2}\chi\quad{I_{P}(\chi)}\sin_{\chi}\quad{\mathbb{d}\chi}}}{\int_{0}^{\pi}{{I_{P}(\chi)}\sin_{\chi}\quad{\mathbb{d}\chi}}}.}$Where I_(P)(χ) is the angular distribution of a directional vector P (inthis case, the PET chain direction) as measured with respect to areference direction, in this case the fiber axis.

In PET there does not exist a crystalline reflection in the direction ofthe PET chains. Thus, to determine the Herman orientation function forPET chains a well recognized geometric relationship is utilized todevelop the square cosine term.(cos² σ)=1−0.8786(cos² χ₍₀₁₀₎ )−0.7733(cos² χ₍₁₁₀₎ )−0.3481(cos²χ₍₁₀₀₎),where σ is the relative angle of the PET chain axis, and χ_((hk0)) arethe relatives angles of the (hk0) crystalline reflections. Thisrelationship was described by Z. Wilchinsky in Journal of AppliedPhysics 30, 792 (1959) the contents of which are incorporated herein byreference.

The <cos² χ_((hk0))> terms can be numerically computed by extracting theI_((hk0))(χ) distributions from the measured diffraction patterns.Angular distributions were computed by integrating the pattern signalsover a 0.7° range of 2θ values centered on the following positions:17.65° for the (010) reflection, 22.75° for the (110) reflection, and25.35° for the (100) reflection. Distributions of x-ray peaks for thehigh shrink and low shrink yarn segments (used for purposes ofintegration) are shown in FIGS. 7A and 7B. Because of the limiteddetector area, distributions were extrapolated out to the full 180°range by assuming the signal at high angles was due solely to amorphousscattering. This amorphous baseline was subtracted from thedistributions before numerical integration.

Results from the numerical determination of the Herman orientationfunction (ƒ_(c)) are shown in Table II below. As shown, the low-shrinkyarn sample possessed a measurably higher level of orientation. TABLE IIHigh Shrink Low Shrink <cos{circumflex over ( )}2(θ100)> 0.060 0.038<cos{circumflex over ( )}2(θ110)> 0.087 0.062 <cos{circumflex over( )}2(θ010)> 0.108 0.083 <cos{circumflex over ( )}2(σ)> 0.817 0.866Herman fc 0.725 0.799

In order to confirm the legitimacy of the crystalline orientationevaluations on the treated yarn of the present invention, a controlanalysis was conducted on a standard fully drawn 265 denier 36 filamentpartially oriented PET yarn that had been cold drawn with a 2.1 drawratio and heat set at 220 C. Three samples were taken from segments 6 to12 inches apart along the length of the yarn and x-ray patterns weregenerated using 45 minute exposures. An air scattering frame was alsoacquired and subtracted from the data before analysis. The samecalculations were performed as described above. The Herman orientationfunction calculated based on the measurements of these samples rangedfrom 0.819 to 0.853 which is a difference of 0.034. This is less thanhalf the difference of 0.074 measured for the high shrink and low shrinkportions of the yarn. Thus, there exists a much greater variation incrystalline orientation between portions of the yarns of the presentinvention following heat treatment than in standard yarns.

Based on the evaluations carried out it may be seen that the interlacednodes along the yarn give rise to the high shrink portions of the yarn.Moreover, upon application of heat treatment these high shrink portionsshrink to a greater degree and have a lower level of crystallineorientation (as measured by the Herman Orientation Function) than thelow shrink portions. Moreover, the degree of variation in crystallineorientation along the length of the yarns of the present invention issubstantially greater than variations in standard yarns.

Fabric Formation:

As will be appreciated through reference to FIG. 2, subsequent to theintroduction of variable heat treatment across portions of the yarn tointroduce the above-described variable shrinkage characteristics, theyarn 122′ may thereafter be heat treated directly to release shrinkagepotential or may be formed into a fabric for subsequent activation ofheat. That is, the formation yarn 122′ may be formed into a greigefabric prior to activation of the self texturing and shrinkagecharacteristics. Activation may be effected by heat application such asduring finishing and/or dying or any other suitable elevated temperatureprocedure. However, due to the variable heat treatment history atsegments along the formation yarn 122′, when the formed greige fabric isheat set and/or dyed at prolonged elevated temperatures, segments of thefabric-forming yarn react in dramatically different fashions therebyimparting a variability to the finished fabric. In particular, portionsof the yarns which made up the interlace nodes 152 and adjacent areasand which did not undergo a uniform heat treatment during drawing tendto undergo selective shrinkage and self texturing during the heatsetting and/or dyeing operations. As explained above, this shrinkageoccurs as a result of the fact that the shrinkage potential within theseyarn segments has not been relieved previously. Conversely, the yarnportions which were in the loose portions of the yarn between theinterlace nodes do not undergo substantial shrinking during the heatsetting and dyeing operation since shrinkage potential has been relievedpreviously.

A resultant fabric structure following heat treatment and dyeing isillustrated in FIG. 8. As shown, although the same yarns 122′ areutilized throughout the face portion 116 of the fabric 110, discretesegments of those yarns have undergone shrinkage so as to form segments160 of self textured entangled construction across the fabric. Thesegments of the yarns which have undergone uniform heat treatment duringthe initial drawing operation do not undergo such shrinkage and thusdefine arrangements of substantially unaltered surface loops 162 whereinthe filaments remain substantially aligned with relatively low levels ofcrimping and entanglement.

As in the individual yarn samples evaluated, due to the shrinkage of thefilaments at different yarn segments in the fabric, the filaments withinthe self textured segments 160 of the face are characterized by asubstantially greater diameter than the filaments in the unalteredsurface loops. By way of example only, for purposes of comparisonphotomicrographs are provided of filament cross sections in exemplarylow shrink yarn portions (FIG. 9) as well as in self textured highshrink yarn segments (FIG. 9A).

It is contemplated that in order to realize the aesthetic and tactilebenefits of the variable shrinkage zones in a formed fabric, thefilaments making up the self-textured segments will preferably have anaverage diameter at least about 25 percent greater (more preferably atleast about 50 percent greater) than the average diameter of thefilaments forming the low shrink portions. For yarns formed fromfilaments with non-circular cross-sections the difference between thehigh shrink and low shrink portions may be measured in terms ofcross-sectional area. For yarns formed from either circular ornon-circular filaments, the high shrink segments will preferably have anaverage cross-sectional area at least about 1.56 times (more preferablyat least about 2.25 times) the average area of the filaments forming thelow shrink segments. In the illustrated exemplary constructions, acomparison of the filaments of FIGS. 9 and 9A shows that these levelsare met and that some of the filaments in the self textured high shrinksegments are at least twice the diameter of some of the filaments in thelow shrink portions. Thus, for yarns formed from non-circular filamentsit is contemplated that at least a portion of the filaments in the highshrink segments will have a cross-sectional area 4 times the area ofsome filaments forming the low shrink segments.

By way of example only, within a yarn 122′ according to the presentinvention it is contemplated that the number of interlace nodes willpreferably be in the range of about 10 to 40 nodes per meter with eachnode taking up about 0.6 to about 1.3 cm. Thus, it is contemplated thatzones of high retained shrinkage potential will preferably make up about6% to about 52% percent of the total length of the yarn and will morepreferably make up about 25% of the total length of the yarn.

A potential benefit of the present invention is that in a fabric theself-textured segments of heat shrunk yarn are arranged across thesurface of the fabric in a substantially random arrangement. Thisimparts a substantially natural random look which may be desirable inmany instances. Moreover, since the self-textured zones undergo heatshrinkage as a result of activating intrinsic heat shrink potential,such shrinkage occurs without embrittlement thereby enhancing a softfeel and avoiding filament breakage leading to undesirable shredding. Inthis regard it is to be understood that the terms “self texturing” or“self-crimping” refers to the characteristic that the filaments have acrimped construction after shinkage without the application of externalcrimping or texturizing procedures.

As previously indicated, after self-texturing takes place, the highshrink portions of the yarn have a lower level of crystallineorientation than the low shrink portions. In this regard it iscontemplated that the level of crystalline orientation of the low shrinkportions of the yarn as measured by the Herman Orientation Function willon average be at least 5% greater (and more preferably at least 10%greater) than the level of crystalline orientation of the high shrinkportions.

The invention may be further understood through reference to thefollowing non-limiting examples.

EXAMPLE I

A 115 denier 36 filament semi-dull round partially oriented polyesteryarn was subjected to a 1.143 draw across a contact Dowtherm heaterplate operated at a temperature of 200 C. The heater contact length was17 inches and the yarn was taken up off of the heater at a rate of 600yards per minute. The yarns were spaced at a density of approximately17.4 yarns per inch across the heater. The warper tension was set at 25to 30 grams. Overall draw ratio was 1.165. Measurements of the postdrawn yarn indicated a linear density of 100.5 denier and a boilingwater shrinkage of 14.7%. The drawn yarn was knitted into the face of a2 bar Tricot knit fabric with the ground being formed of a 70 denier 36filament semi-dull round fully warpdrawn polyester. The bar 1 (faceyarn) runner length was 102 inches. The bar 2 (ground yarn) runnerlength was 46 inches. The knitting machine was fully threaded. Theresultant fabric had 60 coarses per inch. The fabric was jet dyedaccording to a standard disperse dye cycle at 280° F., held for 20minutes with a 2° F. per minute temperature ramp up. The fabric was wetpad tenter dried at a temperature of 300° F. passing through the tenterat 20 yards per minute. The exit width after drying was 59.5 inches. Theresultant fabric had random high loops with relatively greater orientedcrystalline regions than the low loops which were characterized by verylow order orientation of the crystals as measured by wide angle X-rayscattering.

EXAMPLE 2

A 115 denier 36 filament semi-dull round partially oriented polyesteryarn was subjected to a 1.143 draw across a contact Dowtherm heaterplate operated at a temperature of 175 C. The heater contact length was17 inches and the yarn was taken up off of the heater at a rate of 600yards per minute. The yarns were spaced at a density of approximately17.4 yarns per inch across the heater. The warper tension was set at 25to 32 grams. Overall draw ratio was 1.165. Measurements of the postdrawn yarn indicated a linear density of 100.0 denier and a boilingwater shrinkage of 12.04%. The drawn yarn was knitted into the face of a4 bar 56 gauge Raschel knit fabric. The bar 1 yarn (tie down stitch) bar2 yarn (tie down stitch) and bar 4 (ground yarn) were all formed of 70denier 36 filament semi-dull round fully warpdrawn polyester. The faceyarn was threaded in Bar 3. The bar 1 runner length was 60 inches. Thebar 2 runner length was 60 inches. The bar 3 (face yarn) runner lengthwas 102 inches. The bar 4 runner length was 60 inches. The resultantfabric had 49.5 coarses per inch. The fabric was jet dyed at 280° F.,held for 20 minutes with a 2° F. per minute temperature ramp up. Thefabrics were wet pad tenter dried at a temperature of 300° F. passingthrough the tenter at 20 yards per minute. The exit width after dryingwas 53 inches. The resultant fabric had random high loops withrelatively greater oriented crystalline regions than the low loops whichwere characterized by very low order orientation of the crystals asmeasured by wide angle X-ray scattering. The tiedown stitchingpronounced the height of the higher loops.

1. A multi-filament yarn comprising a plurality of interlace nodesdisposed along the length of said yarn, wherein said yarn ischaracterized by variable retained heat shrinkage potential at segmentsalong its length such that segments of said yarn containing saidinterlace nodes have a retained heat shinkage potential in excess ofsegments of said yarn between said interlace nodes such that uponapplication of uniform heat to said yarn, the segments of said yarncontaining said interlace nodes exhibit enhanced shrinkage and selftexturing relative to the segments of said yarn between said interlacenodes such that following said application of uniform heat to said yarn,filaments within the segments of said yarn containing said interlacenodes are characterized by an average cross-sectional area at least 1.56times the average cross-sectional area of yarn filaments in the segmentsof said yarn between said interlace nodes.
 2. The invention as recitedin claim 1, wherein said yarn is a multi-filament polyester yarn.
 3. Theinvention as recited in claim 1, wherein said yarn is a multi-filamentpolypropylene yarn.
 4. The invention as recited in claim 1, wherein saidyarn is a multi-filament nylon yarn.
 5. The invention as recited inclaim 1, wherein said yarn comprises about 10 to 40 interlace nodes permeter along its length.
 6. The invention as recited in claim 1, whereinthe interlace nodes occupy about 6% to about 52% of the length alongsaid yarn.
 7. The invention as recited in claim 6, wherein the interlacenodes occupy about 25% of the length along said yarn.
 8. Amulti-filament yarn comprising a plurality of interlace nodes disposedalong the length of said yarn, wherein said yarn is characterized byvariable retained heat shrinkage potential at segments along its lengthsuch that segments of said yarn containing said interlace nodes have aretained heat shinkage potential in excess of segments of said yarnbetween said interlace nodes such that upon application of uniform heatto said yarn, the segments of said yarn containing said interlace nodesexhibit enhanced self texturing relative to the segments of said yarnbetween said interlace nodes and such that following said application ofuniform heat to said yarn, the average level of crystalline orientationof filaments within the segments of said yarn between said interlacenodes as measured by the Herman Orientation Function is at least 5%greater than the average level of crystalline orientation of filamentswithin the segments containing said interlace nodes.
 9. The invention asrecited in claim 8, wherein the average level of crystalline orientationof filaments within the segments of said yarn between said interlacenodes as measured by the Herman Orientation Function is at least 6%greater than the average level of crystalline orientation of filamentswithin the segments containing said interlace nodes.
 10. The inventionas recited in claim 8, wherein the average level of crystallineorientation of filaments within the segments of said yarn between saidinterlace nodes as measured by the Herman Orientation Function is atleast 7% greater than the average level of crystalline orientation offilaments within the segments containing said interlace nodes.
 11. Theinvention as recited in claim 8, wherein the average level ofcrystalline orientation of filaments within the segments of said yarnbetween said interlace nodes as measured by the Herman OrientationFunction is at least 8% greater than the average level of crystallineorientation of filaments within the segments containing said interlacenodes.
 12. The invention as recited in claim 8, wherein the averagelevel of crystalline orientation of filaments within the segments ofsaid yarn between said interlace nodes as measured by the HermanOrientation Function is at least 9% greater than the average level ofcrystalline orientation of filaments within the segments containing saidinterlace nodes.
 13. The invention as recited in claim 8, wherein saidyarn is a multi-filament polyester yarn.
 14. A multi-filament yarncomprising a plurality of interlace nodes disposed along the length ofsaid yarn, wherein said yarn is characterized by variable retained heatshrinkage potential at segments along its length such that segments ofsaid yarn containing said interlace nodes have a retained heat shinkagepotential in excess of segments of said yarn between said interlacenodes such that upon application of uniform heat to said yarn, thesegments of said yarn containing said interlace nodes exhibit enhancedshrinkage and self texturing relative to the segments of said yarnbetween said interlace nodes such that following said application ofuniform heat to said yarn, filaments within the segments of said yarncontaining said interlace nodes are characterized by an averagecross-sectional area at least 1.56 times the average cross-sectionalarea of yarn filaments in the segments of said yarn between saidinterlace nodes and such that the average level of crystallineorientation of filaments within the segments of said yarn between saidinterlace nodes as measured by the Herman Orientation Function is atleast 5% greater than the average level of crystalline orientation offilaments within the segments containing said interlace nodes.
 15. Theinvention as recited in claim 14, wherein the average level ofcrystalline orientation of filaments within the segments of said yarnbetween said interlace nodes as measured by the Herman OrientationFunction is at least 6% greater than the average level of crystallineorientation of filaments within the segments containing said interlacenodes.
 16. The invention as recited in claim 14, wherein the averagelevel of crystalline orientation of filaments within the segments ofsaid yarn between said interlace nodes as measured by the HermanOrientation Function is at least 7% greater than the average level ofcrystalline orientation of filaments within the segments containing saidinterlace nodes.
 17. The invention as recited in claim 14 wherein theaverage level of crystalline orientation of filaments within thesegments of said yarn between said interlace nodes as measured by theHerman Orientation Function is at least 8% greater than the averagelevel of crystalline orientation of filaments within the segmentscontaining said interlace nodes.
 18. The invention as recited in claim14, wherein the average level of crystalline orientation of filamentswithin the segments of said yarn between said interlace nodes asmeasured by the Herman Orientation Function is at least 9% greater thanthe average level of crystalline orientation of filaments within thesegments containing said interlace nodes.
 19. The invention as recitedin claim 14, wherein said yarn is a multi-filament polyester yarn. 20.The invention as recited in claim 14, wherein following said applicationof uniform heat to said yarn, filaments within the segments of said yarncontaining said interlace nodes are characterized by an averagecross-sectional area at least 1.56 times the average cross-sectionalarea of yarn filaments in the segments of said yarn between saidinterlace nodes.